Support pytest version >= 4.1

[kondratyev-nv]

pytest-describe plugin is not working with pytest 4.0 or later.

=========================================== ERRORS ============================================
_______________ ERROR collecting test/test_samples/pytest/test/describe_test.py _______________
.tox/py27/local/lib/python2.7/site-packages/pytest_describe/plugin.py:110: in _getobj
    return self._importtestmodule()
.tox/py27/local/lib/python2.7/site-packages/pytest_describe/plugin.py:119: in _importtestmodule
    copy_markinfo(module, self.funcobj)
.tox/py27/local/lib/python2.7/site-packages/pytest_describe/plugin.py:60: in copy_markinfo
    from _pytest.mark import MarkInfo
E   ImportError: cannot import name MarkInfo
!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!
=================================== 1 error in 0.75 seconds ===================================

This error appears for the test from sample

import pytest


def describe_list():

    @pytest.fixture
    def list():
        return []

    def describe_append():

        def adds_to_end_of_list_passed(list):
            list.append('foo')
            list.append('bar')
            assert list == ['foo', 'bar']

    def describe_remove():

        @pytest.fixture
        def list():
            return ['foo', 'bar']

        def removes_item_from_list_passed(list):
            list.remove('foo')
            assert list == ['bar']

It looks like this happens due to changes in mark API since version 4.0, for example, see https://github.com/pytest-dev/pytest/blob/master/doc/en/deprecations.rst#somefunctionmarkname.

[ropez]

This looks like it might require some work. Is there any chance you can look into this, and make a PR?

[Pankejk]

I like this plugin and I have the same issue. +1

[kondratyev-nv]

@ropez I have tried to run tests with various versions, and it looks like no main code changes needed for newer python versions and pytest up to 4.0.2. I think of making a PR on this at least.

As for the upper pytest versions, I'll take a look.

[ropez]

Sorry, I haven't had time to look into this. Are you saying that the issue with importing MarkInfo was not a problem after all?

[kondratyev-nv]

@ropez This is the problem for pytest >= 4.1. Everything is fine with the previous versions, and I have added a couple of tests to be sure. Please see PR #19.

[ropez]

Right, I was a little bit confused because you wrote "4.0 or later" in the original post. I will see if I find some time to look for a solution for 4.1 then.

[kondratyev-nv]

@ropez It looks like I have a working solution. However, the tests are failing with the latest pytest version due to the bug in pytest pytest-dev/pytest#4649. I'll open a PR with the fix after the next pytest patch will be released.

[ropez]

@kondratyev-nv Maybe we should just change -k to -m in those test. I don't remember exactly, but it may well be that I should have used -m in the first place, and it just happened to work, like the comments in the pytest issue suggest.